Pilonidal sinus

What is a pilonidal sinus?

pilonidal_rearA pilonidal sinus is a problem in the natal cleft (area just above the buttocks), which can cause infection.  The condition usually affects young adults.  It is less common in women.


This leaflet will give you information about the benefits and risks to help you make an informed decision.

Why does pilonidal sinus happen?

Hairs fall off the neck or back and collect in the natal cleft.  The hairs can cause small holes to form in the skin or can get into existing holes.

As the hairs carry bacteria, the holes can become infected.  This causes an abscess or a discharge that is released through a tunnel (sinus) out into the skin.  Sometimes the sinus can be quite widespread, with branches and pockets of infection.

What are the indications for surgery?

Surgery is the most dependable way to remove the pilonidal sinus.  Once the area has been fully healed, the infection and any discharge do not usually come back.

Are there any alternatives to surgery?

If an abscess has not formed and you have not had any discharge for the sinus for a while, there is not an immediate need to have the operation.

You can treat an occasional discharge with antibiotics.  However, the infection is likely to come back.

What will happen if I decide not to have the operation?

You may not have any further problems.  However the area can keep on getting infected, causing an abscess or a persistent discharge that can continue for years.

pilonidal_rear2What does the operation involve?

1. Excision

2. Incision and drainage

3. Flap procedures for recurrence such as Bascom, Limberg, Rhomboid flaps

The operation is performed under a general anaesthetic and usually takes about an hour.  Surgeon will remove the sinus and infected tissue, sometimes over a large area

At the end of the operation, your surgeon will decide either to close the wound with stitches or leave it to open.

Before the operation, your surgeon can discuss with you if closing the wound with stitches is likely.

Can complications happen?

The surgeon will try to make your operation as safe as possible.  However, complications can happen.  You should ask your surgeon if there is anything you do not understand.  Your surgeon may be able to tell you if the risk of a complication is higher or lower for you.

The future

Occasionally the pilonidal sinus comes back.  It is important to keep the area free from hairs and as clean as possible to reduce this risk.


Pilonidal sinus is a common problem in young people and is best treated by surgery.  It can cause an abscess or persistent discharge.

Surgery is usually safe and effective.  However, complications can happen.  You need to know about them to help you make an informed decision about surgery.  Knowing about them will also help to detect and treat any problems early.


Arumugam PJ, Chandrasekaran TV, Morgan AR, Beynon J, Carr ND.

The rhomboid flap for pilonidal disease.

Colorectal Dis May 2003; 5: 218-221.

Acknowledgement for leaflet:

Copyright © 2010 EIDO Healthcare LimitedThe operation and treatment information on this website is produced by EIDO Healthcare Ltd and is licensed by <org name>. The intellectual property rights to the  information belong exclusively to EIDO Healthcare Limited. You may not copy, print out, download or otherwise reproduce any of the information other than for your  personal, non-commercial use. The information should not replace advice that your relevant health professional would give you.

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